Polyethylene Glycol–CaCl₂ Coordination Compounds as a Novel Form‐Stable Phase Change Material with Excellent Thermophysical Properties

Abstract

Polyethylene glycols (PEGs) have been extensively studied as phase change materials (PCMs). To overcome the problem of liquid leakage, the authors firstly report a novel form-stable phase change material (FSPCM) using coordination compound. The structure, morphology, thermal property, and thermal stability of the self-prepared samples are determined. The obtained results confirm the existence of coordination bonds between PEG and Ca 2þ species, and no liquid leakage is observed for the synthesized PEG-CaCl 2 composites at temperatures as high as 120 C. The PEG8000-CaCl 2 (1:2) FSPCM exhibits a relatively large latent heat of 147.7 J g À1 , corresponding to 87.8% of that of pure PEG. From the dynamical viewpoint, the activation energy of crystallization process is increased by only 5.2% for the PEG8000-CaCl 2 composite due to the formation of coordination bonds; however, the activation energy is reduced by 18.3% during melting process. After adding 3 wt% conductive carbon black, the heat storage performance of the PEG phase change material can be optimized. The PEG-CaCl 2 composite would be a promising material for thermal energy storage applications and can be used in various engineering fields.

Hydrothermal Carbon‐Doped Polyethylene Glycol as Phase‐Change Materials with Good Thermal Conductivity and Shape‐Stability

“…Figure shows the FT‐IR spectrum of PEG, HTC and different mass ratio HTC/PEG SSPCMs. In the spectrum of PEG, the broad peak at 3420 cm −1 can correspond to the stretching vibrations of the ‐ OH, and at 1613 and 1107 cm −1 , the peaks correspond to the stretching vibrations of C=O and C ‐ O, respectively, and the peaks observed at 953 and 2886 cm −1 are caused by the bending vibration and stretching vibration of C ‐ H, respectively. In the spectrum of HTC, the stretching vibrations of C=O and C=C were observed at 1723 and 1613 cm −1 , respectively, and the peak at 3420 and 1078 cm −1 are attributable to the stretching vibration of ‐ OH and C ‐ O.…”

Polyethylene glycol—based functional composite phase change materials with excellent electrical and thermal conductivities

“…In addition, in the spectra of PEG-CaCl 2 complexes and PEG-CaCl 2 /EG functional composite PCMs, the absorption peak of the Ca-O coordination bond appears at 880 cm −1 , which indicates that the complexes contain coordination bonds and that they play a role in shaping the functional composite. 21 In the FT-IR spectrum of PEG-CaCl 2 /EG functional composite PCMs, there is no new characteristic peak, except for the absorption peak of the main functional groups of PEG-CaCl 2 . In addition, the absorption curves of composites with different EG F I G U R E 2 Thermal energy storage throughout the electro-thermal conversion [Colour figure can be viewed at wileyonlinelibrary.com] content are almost identical.…”

“…24 In our former studies, it was proven that white composite-shaped PCMs can be prepared by the ethanol ligand substitution reaction. 21 First, a certain amount of CaCl 2 was poured into a beaker filled with an appropriate amount of ethanol. In a water bath at 80 C, the liquid was stirred until the CaCl 2 was completely dissolved to form a transparent and clear solution.…”

“…In a previous study, 21 we prepared PEG‐CaCl 2 ‐shaped PCMs by coordination chemistry and coordination substitution technology, which solved the problem of PEG leakage. In addition, acetylene black and CNTs as electrically conductive and thermally conductive matrices improved the poor electrical conductivity and heat conduction of PEG‐CaCl 2 PCMs, respectively, but the matrix quantity was high (20 wt%), thus reducing the energy storage density of PCMs 22,23 …”

Expanded Vermiculite: A Promising Natural Encapsulation Material of LiNO3, NaNO3, and KNO3 Phase Change Materials for Medium‐Temperature Thermal Energy Storage

“…The poor form stability perhaps shows severe corrosive behavior in contact with TES systems . Therefore, PCMs should be encapsulated to be protected from environmental factors, thus increasing the surface area for heat transfer, avoiding corrosion, and controlling volume change during phase change . Form‐stable composite PCMs (fs‐CPCMs) consisting of PCMs and porous encapsulation materials have been developed to avoid liquid leakage .…”